1. Field of the Invention
Embodiments of the present invention generally relate to the support of machinery. More particularly, the invention relates to an apparatus and method for axially supporting a shaft or other mass that is laterally supported.
2. Description of the Related Art
A conventional magnetic suspension assembly is based on the repulsive force which exists between two similar magnetic poles. An example of a conventional magnetic suspension assembly is illustrated in FIG. 1. As shown, the conventional magnetic suspension assembly 10 includes a shaft 15 disposed within a housing 20. As illustrated, a first pair of opposing magnets 25, 30 is positioned on one end of the rotating shaft 15 and a second pair of opposing magnets 35, 40 at another end of the rotating shaft 15, suspending the shaft 15. Note that radial support must be provided by other means to prevent lateral movement and cocking of the suspended structure. This radial support can be provided by several means including conventional bearings or bushings.
As greater and greater loads are placed on the suspended structure, it becomes necessary to increase the magnetic field strength. This can be accomplished by increasing the volume of magnetic material through either increasing the size or adding duplicate pairs of magnets (e.g., magnets 25, 30). Due to structural and form factor machine constraints, it is often not possible to increase the face surface area of the magnets, but rather the depth or thickness must be increased. This is only possible until the thickness is on the order of the face width as further magnetic material added is further away from the active face and is decreased by 1/R. As this limit is approached, one must add additional magnetic pairs. There is a need for a more efficient use of magnetic material to create the increased strength with balance.